JP6901025B1 - tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve wet steering stability performance. SOLUTION: The tire 1 has a tread portion 2 in which a rotation direction F is designated. The block 5 of the tread portion 2 includes a corner portion 10 on the stepping side formed between the block tread surface 6 and the block side wall surface 7 located on the first-come-first-served side in the rotation direction F. The stepping-side corner portion 10 includes a first portion 11 and a second portion 12 in the tire axial direction. The first portion 11 is formed sharper than the second portion 12. In the lateral groove 4, the groove width A in the first portion 11 is larger than the groove width B in the second portion. [Selection diagram] Fig. 1

Description

The present invention relates to a tire.

Patent Document 1 below describes a pneumatic tire having a block on the tread portion. The block has a chamfered block edge. The pneumatic tire is expected to have the effect of equalizing the contact pressure of the block.

JP-A-2002-36824

However, in the above-mentioned Patent Document 1, the steering stability performance on a wet road surface (hereinafter, may be simply referred to as "wet steering stability performance") has not been examined.

The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a tire having improved wet steering stability performance.

The present invention is a tire having a tread portion in which a rotation direction is specified, and the tread portion includes at least one block row in which a plurality of blocks are arranged in the tire circumferential direction, and each of the plurality of blocks is a block. A corner portion on the stepping side formed between the tread surface and the side wall surface of the block located on the first-come-first-served side in the rotation direction is included, and a lateral groove is formed between the blocks. , The first portion and the second portion are included in the tire axial direction, and the first portion is formed sharper than the second portion, and in the plan view of the block, the tire circumferential direction of the first portion. The angle θ1 with respect to the tire is larger than the angle θ2 with respect to the tire circumferential direction of the second portion, and in the lateral groove, the groove width A in the first portion is larger than the groove width B in the second portion.

In the tire according to the present invention, it is desirable that the second portion is chamfered and the first portion is not chamfered.

It is desirable that the second portion of the tire according to the present invention is formed by chamfering, and the first portion is formed by chamfering smaller than that of the second portion.

It is desirable that the tire according to the present invention has an angle θ1 of the first portion with respect to the tire circumferential direction of 45 degrees or more.

It is desirable that the tire according to the present invention has an angle θ1 of the first portion with respect to the tire circumferential direction of 70 degrees or more.

In the tire according to the present invention, it is desirable that the ratio (B / A) of the groove width A of the first portion to the groove width B of the second portion is 0.50 to 0.95.

In the tire according to the present invention, it is desirable that the second portion is chamfered, and the chamfer width, which is the length of the chamfer in the tire circumferential direction, is 1.0 to 10.0 mm.

In the tire according to the present invention, the second portion is chamfered, and the chamfer height, which is the height of the chamfer in the tire radial direction, is 0.25 times the length of the chamfer in the tire circumferential direction. It is desirable that:

In the tire according to the present invention, it is desirable that the second portion is chamfered, and the chamfer is formed by a curved surface that is convex outward in the radial direction of the tire.

In the tire according to the present invention, it is desirable that the second portion is chamfered and the chamfer is formed on a flat surface.

In the tire according to the present invention, it is desirable that the block tread has a connecting portion connected to the first portion, and the connecting portion is inclined outward in the radial direction of the tire toward the first portion.

In the tire according to the present invention, it is desirable that each of the plurality of blocks is a shoulder block adjacent to the tread end, and the first portion is arranged closer to the tread end side than the second portion.

In the tire according to the present invention, each of the plurality of blocks includes a kick-out side corner portion formed between the block tread surface and the block side wall surface located on the rear landing side in the rotational direction. It is desirable that the corner portion on the kicking side is chamfered.

In the tire according to the present invention, it is desirable that the tread portion has a main groove extending in the tire circumferential direction, and the second portion is connected to the main groove.

In the tire according to the present invention, each of the plurality of blocks includes a corner portion on the main groove side formed between the block tread and the vertical wall surface of the block formed by the main groove, and the main groove side. It is desirable that the corner portion is chamfered.

In the tire according to the present invention, a belt layer is provided on the tread portion, and the belt layer includes a belt ply in which the belt cord is inclined to one side with respect to the tire axial direction and a belt ply in the belt ply. The belt layer includes an outer belt ply that is arranged outside in the tire radial direction and the belt cord is inclined in the opposite direction to the belt cord of the inner belt ply, and the belt layer is in the tire radial direction of the first portion. It is desirable to be placed in the inner area of the.

By adopting the above configuration, the tire of the present invention can improve the wet steering stability performance.

It is a partial plan view of the tread part of this embodiment. It is a partial perspective view of a block. FIG. 5 is a cross-sectional view taken along the line CC of FIG. It is a partial plan view of the tread part. It is a partial cross-sectional view of a tread part. It is sectional drawing of the block of another embodiment. It is sectional drawing of the block of still another embodiment. It is a perspective view of the block of still another embodiment. It is a perspective view of the block of still another embodiment. It is a perspective view of the block of still another embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partial plan view of the tread portion 2 of the tire 1 of the present embodiment. In the present embodiment, the tire 1 is a pneumatic tire for a passenger car, and is a high-performance tire particularly capable of traveling on public roads and suitable for circuit traveling. The present invention can be applied to, for example, pneumatic tires for motorcycles and heavy loads, and tires of other categories.

As shown in FIG. 1, the tire 1 has a directional pattern in which the rotation direction F is specified. The rotation direction F is indicated by characters or symbols on, for example, a sidewall portion (not shown).

The tread portion 2 includes at least one block row 5R in which a plurality of blocks 5 are arranged in the tire circumferential direction. The block row 5R includes a lateral groove 4 formed between the blocks 5.

Each block 5 includes a block tread 6, a block side wall surface (sometimes referred to as a “first block side wall surface” in the present specification) located on the first-come-first-served side in the rotation direction F, and a block tread 6 and a first. A stepping-side corner portion 10 formed between the block side wall surface 7 and the block side wall surface 7 is formed.

The block tread 6 is a ground contact surface of the block 5 that touches the ground when a normal load is applied to the tire 1 in the normal state and the tire 1 touches the ground at a camber angle of 0 degrees.

The "normal state" is a state in which the tire 1 is rim-assembled on the normal rim, the normal internal pressure is applied, and there is no load. In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in the normal state.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire 1 is based. For example, "standard rim" for JATMA, "Design Rim" for TRA, and ETRTO. If so, it is "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which Tire 1 is based. For JATMA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS" The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Regular load" is the load defined for each tire in the standard system including the standard on which Tire 1 is based. For JATMA, "maximum load capacity", for TRA, "TIRE LOAD" The maximum value described in "LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

FIG. 2 is a perspective view of the block 5 as viewed from the side wall surface side of the first block. As shown in FIG. 2, the stepping-side corner portion 10 includes the first portion 11 and the second portion 12 in the tire axial direction. The first portion 11 is formed sharper than the second portion 12. Such a first portion 11 relatively increases the contact pressure of the block tread surface 6 on the stepping side corner portion 10 side and prevents the block 5 from riding on the water film on the wet road surface, thus enhancing the hydro performance. Further, the second portion 12 suppresses an increase in the contact pressure of the block tread surface 6 of the step-on side corner portion 10 and maintains the uniform contact pressure. As a result, the tire 1 of the present embodiment has excellent wet steering stability performance. The "more sharp" means that the angle γ between the normal line n passing through the block tread 6 and the virtual line m extending the block side wall surface 7 connected to the block tread 6 outward in the radial direction of the tire is one of them. The other is smaller than the other. Further, it is desirable that the angle γ is 15 degrees or less, it is more desirable that the angle γ is 10 degrees or less, and it is more desirable that the angle γ is 5 degrees or less. In other words, when the angle γ exceeds 15 degrees, it is desirable to make it non-sharp, when it exceeds 10 degrees, it is more desirable to make it non-sharp, and when it exceeds 5 degrees, it is more desirable to make it non-sharp. When the chamfer 15 described later is formed on the stepping side corner portion 10, it is determined whether or not the chamfer is sharp by the minimum angle γ (shown in FIG. 3) with respect to the normal line n of the chamfer 15.

As shown in FIG. 1, the angle θ1 of the first portion 11 with respect to the tire circumferential direction is formed to be larger than the angle θ2 of the second portion 12 with respect to the tire circumferential direction. Such a first portion 11 further suppresses the block 5 from riding on the water film. Further, the second portion 12 can smoothly discharge the water film to the rear arrival side (tread end Te side) of the lateral groove 4 in the rotation direction F by utilizing the rotation of the tire 1.

In the lateral groove 4, the groove width A in the first portion 11 is formed to be larger than the groove width B in the second portion 12. As a result, the water film whose ride on the block 5 is suppressed by the first portion 11 can be sufficiently discharged into the lateral groove 4. Further, in the lateral groove 4, the flow velocity at the time of drainage is smaller in the first portion 11 than in the second portion 12 in which the angle θ2 is relatively small. Therefore, by making the groove width A relatively large, the water film in which the riding is suppressed can be discharged more smoothly. In the present specification, each of the groove widths A and B is a length orthogonal to the groove center line 4c, and is an average groove width with respect to the groove length. Further, as the groove widths A and B, in the region where the chamfer is formed, which will be described later, the groove width when the chamfer is not formed is adopted.

In the present embodiment, the block 5 is divided into a tread end Te, a main groove 3 extending in the tire circumferential direction, and a lateral groove 4. As described above, the block 5 of the present embodiment is formed as the shoulder block 5S adjacent to the tread end Te. The block 5 is not limited to the shoulder block 5S, and may be formed as, for example, a middle block or a crown block (not shown) arranged on the tire equator C side of the shoulder block 5S. The tread end Te is the end that comes into contact with the tire 1 on the outermost side in the tire axial direction when a normal load is applied to the tire 1 in the normal state and the tire 1 touches the plane at a camber angle of 0 degrees.

The main groove 3 of the present embodiment extends in a lightning bolt shape along the tire circumferential direction, for example. In the present embodiment, the main groove 3 is inclined in the same direction as the first inclined groove portion 3A and the first inclined groove portion 3A that are inclined to one side with respect to the tire axial direction, and is in the tire axial direction with respect to the first inclined groove portion 3A. It includes a second inclined groove portion 3B that is inclined with respect to a small angle α1. The main groove 3 is not limited to such an aspect.

The first inclined groove portion 3A and the second inclined groove portion 3B are inclined toward the tread end Te side toward the rear arrival side in the rotation direction F, for example. In the present embodiment, the first inclined groove portion 3A and the second inclined groove portion 3B are provided alternately in the tire circumferential direction. The second inclined groove portion 3B is smoothly connected to the lateral groove 4, for example, to form a single groove.

A plurality of lateral grooves 4 of the present embodiment extend in the tire axial direction and are arranged in the tire circumferential direction. The lateral groove 4 connects, for example, the main groove 3 and the tread end Te. In the present embodiment, the lateral groove 4 is inclined toward the tread end Te side toward the rear arrival side in the rotation direction F. Such a lateral groove 4 smoothly discharges water in the main groove 3 to the outside of the tread end Te by utilizing the rotation of the tire.

In the lateral groove 4, for example, the angle α2 with respect to the tire axial direction is continuously reduced toward the tread end Te side. Such a lateral groove 4 further enhances wet steering stability performance. The lateral groove 4 is not limited to such an aspect.

In the present embodiment, the groove wall 4e of the lateral groove 4 forms the first block side wall surface 7 and the second block side wall surface 20 (shown in FIG. 4) which will be described later.

A chamfer 15 is formed in the second portion 12 of the present embodiment. Such a chamfer 15 helps to improve the uniformity of the ground pressure of the block 5. The chamfer 15 is an inclined surface having a shape that is diagonally cut off from the block tread 6 toward the lateral groove 4 and the main groove 3, and when the normal load is applied and the surface is grounded at a camber angle of 0 degrees. This is the surface to be grounded. The chamfering described in the present specification does not include a roundness having a radius of curvature r (shown in FIG. 3) of less than 1 mm, which is formed in the manufacturing process of the tire 1. Further, the first portion 11 of the present embodiment is not chamfered.

FIG. 3 is a cross-sectional view taken along the line CC of FIG. As shown in FIG. 3, the chamfer 15 is formed of, for example, a curved surface 16 that is convex outward in the radial direction of the tire. Such a chamfer 15 can further make the ground pressure in the chamfer 15 more uniform. In the present embodiment, the chamfer 15 is formed so that the radius of curvature r becomes smaller toward the side wall surface 7 of the first block. As a result, the contact pressure on the side wall surface 7 side of the first block on which a larger contact pressure acts can be reduced, the uniformity of the contact pressure can be improved, and the wet steering stability performance can be improved. In the chamfer 15, for example, the radius of curvature r is continuously reduced toward the side wall surface 7 of the first block. The chamfer 15 may be formed by, for example, an arc having a radius of curvature r.

When the chamfer width Lb, which is the length of the chamfer 15 in the tire circumferential direction, is 1.0 mm or more, it is effective for the uniformity of the contact pressure. When the chamfer width Lb is 10.0 mm or less, it is effective in maintaining the rigidity of the block 5 high. In order to effectively exert such an action, the chamfer width Lb is more preferably 2.0 mm or more, more preferably 3.0 mm or more, further preferably 9.0 mm or less, and further preferably 8.0 mm or less.

In order to improve the uniformity of the ground pressure while maintaining the rigidity of the block 5 in the tire circumferential direction, the chamfering width Lb of the block 5 is the length of the block 5 in the tire circumferential direction (maximum length in the tire circumferential direction line). S) 10% or more of La is desirable, and 15% or more is more desirable. The chamfer width Lb of the block 5 is preferably 25% or less of the length La of the block 5, and more preferably 20% or less.

When the chamfer height Hb, which is the height of the chamfer 15 in the tire radial direction, is 0.25 times or less of the chamfer width Lb, the chamfer 15 can be effectively grounded, so that the uniformity of the ground pressure is improved. Wet steering stability performance can be improved. When the chamfer height Hb is 0.08 times or more the chamfer width Lb, the contact pressure of the chamfer 15 can be reduced, so that the uniformity can be improved. In order to exert such an action more effectively, the chamfer height Hb is more preferably 0.22 times or less of the chamfer width Lb, and further preferably 0.10 times or more.

As shown in FIG. 1, the first portion 11 is arranged closer to the tread end Te side than the second portion 12. As a result, the water film whose invasion into the block tread 6 is prevented from entering the block tread 6 in the first portion 11 is smoothly discharged from the tread end Te through the lateral groove 4.

FIG. 4 is a partial plan view of the tread portion 2. As shown in FIG. 4, the first portion 11 and the second portion 12 of the block 5 are connected so as to form a smooth curve without having a bent portion. Since the first portion 11 and the second portion 12 reduce the rigidity step of the block 5, the wet steering stability performance is enhanced.

In order to effectively exert the above-mentioned action, the angle θ1 of the first portion 11 is preferably 45 degrees or more, and more preferably 70 degrees or more. Further, the angle θ2 of the second portion 12 is preferably smaller than 45 degrees, and more preferably smaller than 70 degrees. More specifically, it is desirable that the first portion 11 is formed outside the tire axial direction from a position where the angle θ1 is 45 degrees, and is formed outside the tire axial direction from a position where the angle θ1 is 70 degrees. , More desirable. In the present embodiment, the first portion 11 is formed on the outer side in the tire axial direction from the position where the angle θ1 is 80 degrees.

The first portion 11 of the present embodiment has an inner portion 11a connected to the second portion 12, which is shorter in the tire axial direction than the inner portion 11a, and has an inner portion connecting the inner portion 11a and the tread end Te. It includes an outer portion 11b having an angle θ1 smaller than that of 11a. The outer portion 11b has, for example, an angle smaller than the angle θ2 of the second portion 12. In the present embodiment, the outer portion 11b is formed sharper than the second portion 12, and the chamfer is not formed.

If the groove width B in the second portion 12 is excessively small, the hydro performance may deteriorate. If the groove width A in the first portion 11 is excessively large, the rigidity in the tire circumferential direction in the first portion 11 of the block 5 becomes small, and the wet steering stability performance may deteriorate. Therefore, the ratio (B / A) of the groove width A of the first portion 11 to the groove width B of the second portion 12 is preferably 0.50 or more, and more preferably 0.70 or more. The ratio (B / A) is preferably 0.95 or less, and more preferably 0.90 or less.

Further, the ratio (B / A) is such that the difference Δγ between the angle γ of the first portion 11 and the angle γ of the second portion 12 is 0.50 to 0.95 between 5 and 10 degrees. desirable. If the difference Δγ is less than 5 degrees or more than 10 degrees, the water film cannot be discharged in a well-balanced manner between the first portion 11 and the second portion 12, and the improvement in wet steering stability performance may be reduced. There is.

Further, the ratio (B / A) is preferably 0.50 to 0.95 when the chamfer width Lb of the second portion 12 is 1.0 to 10.0 mm. When the chamfer width Lb is less than 1.0 mm or more than 10.0 mm, the water film is not effectively removed by the second portion 12, and the wet steering stability performance may not be improved.

Further, the ratio (B / A) is preferably the groove width ratio of the lateral grooves 4 formed between the shoulder blocks. As a result, the water film in the lateral groove 4 can be smoothly discharged from the tread end Te, so that the wet steering stability performance can be effectively exhibited.

Although not particularly limited, it is desirable that the length L1 of the first portion 11 in the tire axial direction is equal to the length L2 of the second portion 12 in the tire axial direction. This has the effect of improving the uniformity of the ground pressure while improving the wet steering stability performance. In order to effectively exert such an action, the ratio (L1 / L2) of the length L1 of the first portion 11 to the length L2 of the second portion 12 is preferably 0.3 or more, and 0.4 or more. Is even more desirable. The ratio (L1 / L2) is preferably 0.7 or less, and more preferably 0.6 or less.

As shown in FIG. 2, in the chamfer 15 of the block 5 of the present embodiment, the chamfer width Lb (shown in FIG. 3) is the same along the lateral groove 4, and the chamfer width Lb is the first portion. It includes a changing portion 18 that becomes smaller toward the 11 side. Such a changing portion 18 reduces the rigidity step of the stepping side corner portion 10 of the block 5 to maintain high wet steering stability performance. In the present embodiment, the chamfer height Hb of the changing portion 18 becomes smaller toward the first portion 11 side.

As shown in FIG. 4, in the present embodiment, the block 5 is a block side wall surface (in this specification, it may be referred to as a “second block side wall surface”) 20 located on the back-attached side in the rotation direction F. And the block vertical wall surface 21 formed by the main groove 3. As a result, the block 5 has a kick-out side corner portion 22 formed between the block tread 6 and the second block side wall surface 20, and a main groove side corner formed between the block tread 6 and the block vertical wall surface 21. The unit 23 and the like are included.

A chamfer 24 is formed on the kick-out side corner portion 22 of the present embodiment. The kick-out side corner portion 22 is formed with chamfers 24, for example, in all directions in the length direction thereof. Further, a chamfer 25 is formed in the main groove side corner portion 23 of the present embodiment. The main groove side corner portion 23 has chamfers 25 formed in all directions in the length direction, for example. As a result, the uniformity of the ground pressure of the block 5 is improved. In the present embodiment, the chamfer 24 and the chamfer 25 mainly adopt the same shape as the chamfer 15. Therefore, regarding the chamfer 24 and the chamfer 25, only the portion different from the chamfer 15 will be described. The chamfer 24 and the chamfer 25 are not limited to such an embodiment, and may have a shape different from that of the chamfer 15.

The chamfer width Le, which is the length of the chamfer 25 in the tire axial direction, is preferably 12.5% or less of the length (maximum length) Ld of the block 5 in the tire axial direction, and more preferably 10.0% or less. The chamfer width Le of the chamfer 25 is preferably 2.5% or more below the length Ld of the block 5 in the tire axial direction, and more preferably 5.0% or more.

A sipe 26 extending in the tire axial direction is provided on the block tread 6 of the block 5 of the present embodiment. For example, one sipe 26 is provided in each of the blocks 5. Such a sipe 26 exerts a scratching effect on a wet road surface to enhance wet steering stability performance. In the present specification, a sipe is defined as a groove-like body having a width of less than 1.0 mm, and is classified as a groove having a groove width of 1.0 mm or more.

The sipe 26 extends from, for example, the tread end Te and terminates within block 5. Further, in the present embodiment, the sipe 26 is inclined toward the tread end Te side toward the rear arrival side in the rotation direction F. Such a sipe 26 can smoothly discharge the water film between the block tread 6 and the road surface to the outside of the tread end Te while suppressing a decrease in the rigidity of the block 5.

FIG. 5 is a partial cross-sectional view of the tread portion 2. As shown in FIG. 5, the tread portion 2 is provided with, for example, a belt layer 8 extending in the tire axial direction. In the belt layer 8 of the present embodiment, the belt ply 8a in which the belt cord (not shown) is inclined to one side with respect to the tire axial direction and the belt cord are inclined in the opposite direction to the belt cord of the inner belt ply 8a. Includes an outer belt ply 8b. The belt layer 8 of this embodiment is made of a well-known material.

The belt layer 8 is arranged, for example, in the inner region R of the first portion 11 in the tire radial direction. As a result, the rigidity of the block 5 is increased, and the contact pressure of the first portion 11 is increased, so that the block 5 is further suppressed from riding on the water film. In the present embodiment, the belt layer 8 is arranged in the entire inner region R of the first portion 11.

FIG. 6 is a cross-sectional view of the block 5 of another embodiment (corresponding to the cross-sectional view taken along the line CC of FIG. 1). The same components as the components of block 5 of the present embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 6, the chamfer 15 of this embodiment is formed, for example, by a plane 27. The chamfer 15 may be formed by a flat surface 27 connected to the block tread 6 and a curved surface 16 connecting the flat surface 27 and the first block side wall surface 7 (not shown).

FIG. 7 is a cross-sectional view of the block 5 of still another embodiment (corresponding to the cross-sectional view taken along the line DD of FIG. 2). The same components as the components of block 5 and block 5 shown in FIG. 6 of the present embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 7, the block tread 6 of this embodiment is provided with a connecting portion 29 connected to the first portion 11 of the first block side wall surface 7.

The connecting portion 29 is inclined outward in the radial direction of the tire toward, for example, the first portion 11. Such a connecting portion 29 increases the block height of the first portion 11 to further increase the ground pressure of this portion, so that the hydro performance is further improved.

Further, in order to enhance the above-mentioned action in a well-balanced manner, the height Hc of the connecting portion 29 is preferably 0.25 times or less of the length Lc of the connecting portion 29 in the tire circumferential direction, and is 0.22 times or less. It is even more desirable to have. The height Hc of the connecting portion 29 is preferably 0.05 times or more the length Lc of the connecting portion 29, and more preferably 0.08 times or more.

Although not particularly limited, the length Lc of the connecting portion 29 is preferably 1.0 mm or more, more preferably 2.0 mm or more, and even more preferably 3.0 mm or more. The length Lc of the connecting portion 29 is preferably 10.0 mm or less, more preferably 9.0 mm or less, and even more preferably 8.0 mm or less.

FIG. 8 is a perspective view of the block 5 of the other embodiment as viewed from the side wall surface 7 side of the first block. The same components as the components of block 5 and blocks 5 shown in FIGS. 6 and 7 of the present embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 8, the block 5 of this embodiment is formed by a chamfer 30 in which the first portion 11 is smaller than the second portion 12. Such a block 5 can further improve the uniformity of the ground pressure. The chamfer 30 of the first portion 11 of this embodiment is formed, for example, with the same chamfer width Lb and the same chamfer height Hb in the length direction thereof.

FIG. 9 is a perspective view of the block 5 of the other embodiment as viewed from the side wall surface 7 side of the first block. The same components as the components of block 5 and blocks 5 shown in FIGS. 6 to 8 of the present embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 9, in the stepping-side corner portion 10 of the block 5 of this embodiment, the chamfer 15 of the second portion 12 and the first portion 11 are connected by a stepped surface 31 extending in the radial direction of the tire. .. In such a stepping-side corner portion 10, the contact pressure becomes relatively high in the vicinity of the stepped surface 31, so that the block 5 is further suppressed from riding on the water film.

FIG. 10 is a perspective view of the block 5 of the other embodiment as viewed from the side wall surface 7 side of the first block. The same components as the components of block 5 and blocks 5 shown in FIGS. 6 to 9 of the present embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 10, in the block 5 of this embodiment, the chamfer 15 of the second portion 12 is formed by the changing portion 18 without forming the non-changing portion 17.

Although the particularly preferable embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified into various embodiments.

Pneumatic tires for passenger cars were manufactured and the running performance of each test tire on wet roads was tested. The sample tire has a tread portion including a block having the basic shapes shown in FIGS. 1 and 2, and the shapes other than this block are common. The test method and common specifications for tires are as follows.
Tire size: 235 / 40R18
Rim size: 18 x 12J
Internal pressure: 200kPa (all wheels)

<Lap time and steering stability performance>
The test driver ran the test vehicle equipped with the test tires on a circuit test course on an asphalt road surface at a depth of 5 mm. Then, the difference (T-Tn) between the reference time T, which is the lap time (running time) when the reference sample tire is attached (reference example), and the lap time Tn when the tires of each comparative example and the embodiment are attached. ) Was calculated. The lap time result is represented by an exponent in which the difference Δt between the lap times of Comparative Example 1 and the reference example is 100. In addition, the steering stability performance was evaluated by a test driver by a test driver in consideration of the lap time. The result of steering stability performance is indicated by a score of 100 for the tire of the reference example. The higher the numerical value, the better the test results.
Test vehicle: Passenger car that can run in Group GT3 (auto racing) In "A" in Table 1, the first part (sharp corner part) where chamfering is not formed is the corner part where the angle with respect to the tire circumferential direction is closest to 90 degrees. , And its adjacent corners. “B” indicates that all the corners on the stepping side are chamfered. “C” indicates that all the corners on the stepping side are not chamfered (all sharp aspects). “D” indicates that the stepping-side corner portion includes a first portion in which a chamfer is not formed and a second portion in which a chamfer is formed. "E" indicates that the second part is sharper than the first part.
The "angle of the first portion" means that the first portion is formed outside the tire axial direction from the angle (angle with respect to the tire circumferential direction) described in each embodiment.
In Table 3, the embodiment is a mode in which the chamfer is smoothly connected to the block tread, and the comparative example is a mode in which the chamfer is not smoothly connected to the block tread.
The groove width B is the same size in both Examples and Comparative Examples.
The test results are shown in Tables 1-4.

As a result of the test, it was confirmed that the tire of the example had excellent wet steering stability performance.

1 Tire 2 Tread part 4 Horizontal groove 5 Block 6 Block Tread 7 Block Side wall surface 10 Corner part 11 1st part 12 2nd part

Claims (16)

A tire that has a tread portion with a specified direction of rotation.
The tread portion includes at least one block row in which a plurality of blocks are arranged in the tire circumferential direction.
Each of the plurality of blocks includes a corner portion on the stepping side formed between the block tread surface and the block side wall surface located on the first-come-first-served side in the rotation direction.
A lateral groove is formed between the blocks.
The stepping-side corner portion includes a first portion and a second portion in the tire axial direction.
When the angle γ is set between the normal line passing through the block tread and the virtual line extending the block side wall surface connected to the block tread to the outside in the radial direction of the tire.
The angle γ of the first portion is smaller than the angle γ of the second portion.
In the plan view of the block, the angle θ1 of the first portion with respect to the tire circumferential direction is larger than the angle θ2 of the second portion with respect to the tire circumferential direction.
In the transverse grooves, the groove width A at the first portion is much larger than the groove width B of the second portion,
The angle θ1 of the first portion with respect to the tire circumferential direction is 70 degrees or more.
tire. A tire that has a tread portion with a specified direction of rotation.
The tread portion includes at least one block row in which a plurality of blocks are arranged in the tire circumferential direction.
Each of the plurality of blocks includes a corner portion on the stepping side formed between the block tread surface and the block side wall surface located on the first-come-first-served side in the rotation direction.
A lateral groove is formed between the blocks.
The stepping-side corner portion includes a first portion and a second portion in the tire axial direction.
When the angle γ is set between the normal line passing through the block tread and the virtual line extending the block side wall surface connected to the block tread to the outside in the radial direction of the tire.
The angle γ of the first portion is smaller than the angle γ of the second portion.
In the plan view of the block, the angle θ1 of the first portion with respect to the tire circumferential direction is larger than the angle θ2 of the second portion with respect to the tire circumferential direction.
In the lateral groove, the groove width A in the first portion is larger than the groove width B in the second portion.
The ratio (B / A) of the groove width A of the first portion to the groove width B of the second portion is 0.50 to 0.95.
tire. A tire that has a tread portion with a specified direction of rotation.
The tread portion includes at least one block row in which a plurality of blocks are arranged in the tire circumferential direction.
Each of the plurality of blocks includes a corner portion on the stepping side formed between the block tread surface and the block side wall surface located on the first-come-first-served side in the rotation direction.
A lateral groove is formed between the blocks.
The stepping-side corner portion includes a first portion and a second portion in the tire axial direction.
When the angle γ is set between the normal line passing through the block tread and the virtual line extending the block side wall surface connected to the block tread to the outside in the radial direction of the tire.
The angle γ of the first portion is smaller than the angle γ of the second portion.
In the plan view of the block, the angle θ1 of the first portion with respect to the tire circumferential direction is larger than the angle θ2 of the second portion with respect to the tire circumferential direction.
In the lateral groove, the groove width A in the first portion is larger than the groove width B in the second portion.
The second part is chamfered and has a chamfer.
The chamfer is formed by a curved surface that is convex outward in the radial direction of the tire.
tire. A tire that has a tread portion with a specified direction of rotation.
The tread portion includes at least one block row in which a plurality of blocks are arranged in the tire circumferential direction.
Each of the plurality of blocks includes a corner portion on the stepping side formed between the block tread surface and the block side wall surface located on the first-come-first-served side in the rotation direction.
A lateral groove is formed between the blocks.
The stepping-side corner portion includes a first portion and a second portion in the tire axial direction.
When the angle γ is set between the normal line passing through the block tread and the virtual line extending the block side wall surface connected to the block tread to the outside in the radial direction of the tire.
The angle γ of the first portion is smaller than the angle γ of the second portion.
In the plan view of the block, the angle θ1 of the first portion with respect to the tire circumferential direction is larger than the angle θ2 of the second portion with respect to the tire circumferential direction.
In the lateral groove, the groove width A in the first portion is larger than the groove width B in the second portion.
The block tread has a connecting portion connected to the first portion.
The connection portion is inclined outward in the radial direction of the tire toward the first portion.
tire. A tire that has a tread portion with a specified direction of rotation.
The tread portion includes at least one block row in which a plurality of blocks are arranged in the tire circumferential direction.
Each of the plurality of blocks includes a corner portion on the stepping side formed between the block tread surface and the block side wall surface located on the first-come-first-served side in the rotation direction.
A lateral groove is formed between the blocks.
The stepping-side corner portion includes a first portion and a second portion in the tire axial direction.
When the angle γ is set between the normal line passing through the block tread and the virtual line extending the block side wall surface connected to the block tread to the outside in the radial direction of the tire.
The angle γ of the first portion is smaller than the angle γ of the second portion.
In the plan view of the block, the angle θ1 of the first portion with respect to the tire circumferential direction is larger than the angle θ2 of the second portion with respect to the tire circumferential direction.
In the lateral groove, the groove width A in the first portion is larger than the groove width B in the second portion.
Each of the plurality of blocks is a shoulder block adjacent to the tread end.
The first portion is arranged closer to the tread end side than the second portion.
tire. A tire that has a tread portion with a specified direction of rotation.
The tread portion includes at least one block row in which a plurality of blocks are arranged in the tire circumferential direction.
Each of the plurality of blocks includes a corner portion on the stepping side formed between the block tread surface and the block side wall surface located on the first-come-first-served side in the rotation direction.
A lateral groove is formed between the blocks.
The stepping-side corner portion includes a first portion and a second portion in the tire axial direction.
When the angle γ is set between the normal line passing through the block tread and the virtual line extending the block side wall surface connected to the block tread to the outside in the radial direction of the tire.
The angle γ of the first portion is smaller than the angle γ of the second portion.
In the plan view of the block, the angle θ1 of the first portion with respect to the tire circumferential direction is larger than the angle θ2 of the second portion with respect to the tire circumferential direction.
In the lateral groove, the groove width A in the first portion is larger than the groove width B in the second portion.
Each of the plurality of blocks includes a kick-out side corner portion formed between the block tread surface and the block side wall surface located on the rear landing side in the rotation direction.
The kick-out side corner portion is chamfered.
tire. A tire that has a tread portion with a specified direction of rotation.
The tread portion includes at least one block row in which a plurality of blocks are arranged in the tire circumferential direction.
Each of the plurality of blocks includes a corner portion on the stepping side formed between the block tread surface and the block side wall surface located on the first-come-first-served side in the rotation direction.
A lateral groove is formed between the blocks.
The stepping-side corner portion includes a first portion and a second portion in the tire axial direction.
When the angle γ is set between the normal line passing through the block tread and the virtual line extending the block side wall surface connected to the block tread to the outside in the radial direction of the tire.
The angle γ of the first portion is smaller than the angle γ of the second portion.
In the plan view of the block, the angle θ1 of the first portion with respect to the tire circumferential direction is larger than the angle θ2 of the second portion with respect to the tire circumferential direction.
In the lateral groove, the groove width A in the first portion is larger than the groove width B in the second portion.
A belt layer is provided on the tread portion, and the tread portion is provided with a belt layer.
The belt layer is arranged on the inner side of the belt ply in which the belt cord is inclined to one side with respect to the tire axial direction and the outer side of the inner belt ply in the tire radial direction, and the belt cord is arranged in the inner belt ply. Including the said belt cord and an outer belt ply that inclines in the opposite direction.
The belt layer is arranged in the inner region of the first portion in the radial direction of the tire.
tire. A tire that has a tread portion with a specified direction of rotation.
The tread portion includes at least one block row in which a plurality of blocks are arranged in the tire circumferential direction.
Each of the plurality of blocks includes a corner portion on the stepping side formed between the block tread surface and the block side wall surface located on the first-come-first-served side in the rotation direction.
A lateral groove is formed between the blocks.
The stepping-side corner portion includes a first portion and a second portion in the tire axial direction.
When the angle γ is set between the normal line passing through the block tread and the virtual line extending the block side wall surface connected to the block tread to the outside in the radial direction of the tire.
The angle γ of the first portion is smaller than the angle γ of the second portion.
In the plan view of the block, the angle θ1 of the first portion with respect to the tire circumferential direction is larger than the angle θ2 of the second portion with respect to the tire circumferential direction.
In the lateral groove, the groove width A in the first portion is larger than the groove width B in the second portion.
The second part is chamfered, and the first part is not chamfered.
The chamfer includes a non-changing portion in which the chamfer width is the same along the lateral groove and a changing portion in which the chamfer width becomes smaller toward the first portion side.
tire. A tire that has a tread portion with a specified direction of rotation.
The tread portion includes at least one block row in which a plurality of blocks are arranged in the tire circumferential direction.
Each of the plurality of blocks includes a corner portion on the stepping side formed between the block tread surface and the block side wall surface located on the first-come-first-served side in the rotation direction.
A lateral groove is formed between the blocks.
The stepping-side corner portion includes a first portion and a second portion in the tire axial direction.
When the angle γ is set between the normal line passing through the block tread and the virtual line extending the block side wall surface connected to the block tread to the outside in the radial direction of the tire.
The angle γ of the first portion is smaller than the angle γ of the second portion.
In the plan view of the block, the angle θ1 of the first portion with respect to the tire circumferential direction is larger than the angle θ2 of the second portion with respect to the tire circumferential direction.
In the lateral groove, the groove width A in the first portion is larger than the groove width B in the second portion.
The second part is chamfered, and the first part is not chamfered.
The chamfer of the second portion and the first portion are connected by a stepped surface extending in the radial direction of the tire.
tire. The tire according to any one of claims 1 to 7, wherein the second portion is chamfered and the first portion is not chamfered. Any one of claims 1 to 7, wherein the second portion is formed by chamfering, and the first portion is formed by chamfering having a chamfering width and a chamfering height smaller than those of the second portion. Tires listed in. The tire according to any one of claims 2 to 11, wherein the angle θ1 of the first portion with respect to the tire circumferential direction is 45 degrees or more. The second part is chamfered and has a chamfer.
The tire according to any one of claims 1 to 12, wherein the chamfer width, which is the length of the chamfer in the tire circumferential direction, is 1.0 to 10.0 mm. The second part is chamfered and has a chamfer.
The tire according to any one of claims 1 to 13, wherein the chamfer is formed on a flat surface. The tread portion has a main groove extending in the tire circumferential direction.
The tire according to any one of claims 1 to 14, wherein the second portion is connected to the main groove. Each of the plurality of blocks includes a corner portion on the main groove side formed between the tread surface of the block and the vertical wall surface of the block formed by the main groove.
The tire according to claim 15, wherein the main groove side corner portion is chamfered.

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